1. Field of the Invention
This invention relates to a continuous paper cutting unit for cutting perforated continuous paper along the line of perforations.
2. Related Art
A conventional continuous paper cutting unit is shown in FIG. 56 as described in Japanese Patent Laid-Open No. Hei 6-91588.
FIG. 56(a) depicts a continuous paper cutting unit 1. Continuous paper 2 having perforations engages a pin tractor 3 and is taken into the continuous paper cutting unit 1. The continuous paper 2 fed from the pin tractor 3 is transported by means of a paper feed roller 4 and a pinch roller 5 and is further transported past paper cutting boards 6 and 7, which also function as paper reception beds, by means of a paper discharge roller 8 and a pinch roller 9. The continuous paper 2 is transported so that its perforations are positioned in a gap between the boards 6 and 7, and the paper 2 is cut at the perforation position. The cut paper is transported one sheet at a time from the paper reception beds 6, 7 by the paper discharge roller 8 and the pinch roller 9 and stored in a stacker 10.
In the paper cutting portion of FIG. 56(b), shafts 11 each having a flange 18 penetrate paper pressers 12 and 12' and are fixedly secured to a cutter blade attachment member 13. A crank 15 attached to a drive shaft 14 transmits motion produced by rotation of the drive shaft 14 via a connecting rod 16 to the cutter blade attachment member 13. The motion produced by rotation of the drive shaft 14 is reciprocating motion in the vertical direction because a shaft 17 fixedly secured to a cabinet (see FIG. 56 (e)) penetrates a hole of the cutter blade attachment member 13.
The paper pressers 12, 12' are supported by the flanges 18 of the shafts 11, and the cutter blade 19 and the paper pressers 12, 12' are at a sufficient distance from the paper reception beds 6, 7. At this point in time, the paper perforations are transported to the center of the gap between the paper reception beds 6 and 7 (see FIG. 56(c)). As the drive shaft 14 is rotated, the crank 15 rotates, thereby rotating the connecting rod 16 for lowering the cutter blade 19 which is fixedly secured to the cutter blade attachment member 13. As the cutter blade 19 falls, the shafts 11 also fall, so that the lower face of the paper pressers 12, 12' soon reach the paper reception beds 6, 7.
Although the paper pressers 12 and 12' abut the paper reception beds 6 and 7 and stop falling, the cutter blade 19 falls further while compressing springs 20, and the cutter blade 19 soon abuts the perforations of the paper 2, and tears the paper 2 along the perforations (see FIG. 56(d)). A large force acts on the paper 2 as the cutter blade 19 abuts the perforations, but the paper pressers 12 and 12' press the paper due to the repulsion of the spring 20. Thus, the paper 2 is not brought into the gap between the paper reception beds 6 and 7 and the cutter blade 19.
As the drive shaft 14 rotates, the cutter blade 19 rises and soon the paper pressers 12 and 12' are pulled up. Then, the paper feed roller 4 and the paper discharge roller 8 rotate to feed the cut paper 2 into the stacker 10 and transport the subsequent portion of continuous paper 2 forward to a predetermined position. The operational sequence is then repeated.
Japanese Patent Laid-Open No. Sho 50-96136 is an example of another conventional continuous paper cutting unit, and is shown in FIG. 57. In FIG. 57 (a), paper reception beds 21, 22 are placed on a paper discharge passage of a line printer, and continuous paper 2 is discharged from the line printer and guided to the reception beds 21, 22.
Up and down movable paper retainers 23, 24 which act as paper pressers, each having a flat friction face, are pressed down, as required, such that perforations 2a of the continuous paper 2 are positioned at a substantial center of a gap between the paper reception beds 21 and 22. The retainers 23, 24 press both sides of the perforations 2a of the continuous paper 2 against their respective reception bed faces 21, 22 throughout the paper width. The retainers 23 and 24 have rubberpieces 23a and 24a for providing a flat friction face at the tip of the retainers 23, 24.
To cut the paper 2 along the perforations 2a, the paper may be struck at the center throughout the paper width with an up and down movable plate-like blunt instrument 25, which is rounded at the tip 25a, such that both sides of the perforations 2a of the continuous paper 2 are sandwiched between the retainers 23 and 24 and the reception beds 21 and 22.
As shown in FIG. 57(b), a device having a rounded tip 25a shaped like a slope is used as the blunt instrument 25. Since such a blunt instrument would start to press the paper at a lowermost end part 25a', the act of cutting the paper is started at one end of the perforations 2a by using the lowermost end part 25a' of the blunt instrument 25, as shown in FIG. 57(d), to strike against the perforations 2a. Therefore, the paper cutting proceeds from one end of the perforations to the other end as the paper is torn off along the perforations, so that the paper can be cut smoothly.
In Japanese Patent Laid-Open No. Sho 50-96136, a rod 26 pivoting about one point 26c as it is swung downward is also disclosed as a blunt instrument, as shown in FIG. 57(c).